As it is known, several automotive systems require the presence in a vehicle of a backup energy source, to provide electrical energy in substitution, or as an aid to a main power supply of the vehicle, in case of failure or interruption of the same main power supply.
This backup power source is usually kept in a charged state during normal operation, by the main power supply of the vehicle, so as to be readily available as soon as the need arises, for example in case of an accident or crash of the vehicle.
For example, the use of a backup power source coupled to a vehicle closure device has been proposed, in order to supply electrical energy, in case the main power supply of the vehicle fails, so that opening of the closure device is possible even in emergency situations.
It is underlined that the expression “closure device” is used herein to generally indicate any element movable between an open position and a closed position, respectively opening and closing an access to an inner compartment of a motor vehicle, therefore including, boot, rear hatches, bonnet lid or other closed compartments, window regulators, sunroofs, in addition to the side doors of a motor vehicle, to which the following description will make explicit reference, purely by way of example.
Security and safety regulations indeed require opening and closing, for example of the vehicle doors, even in case of failure of the main power supply of the vehicle, or in case of interruptions or breaking of the electrical connection between the main power supply and the vehicle doors; this kind of situation may occur, for example, in case of an accident or crash involving the vehicle.
However, the integration of a backup power source, and of the related electronic circuitry, in automotive systems, such as in vehicle door systems, has proven to be a difficult task, due to size requirements, as also has proven to be difficult meeting desired electrical performance, for example in terms of energy density or current output, especially in automotive operating conditions, requiring, for example, safe operation at very high temperatures (for example up to 100° C.).
Some solutions have been proposed, envisaging use of capacitor elements as backup energy sources in a vehicle, such as those discussed in WO 2005 047628 A1 and FR 2 857 399 A1; however, these solutions have proven not be satisfactory, in particular since they do not provide a reliable control of the electrical performance of the backup energy source during its operation, for example during its recharge.
Moreover, it is known that backup energy source solutions, designed for use in other technical fields, are generally not able to meet the specific requirements required of the automotive field.
A need is therefore felt in the automotive field for an optimized backup power source, able to reliably supply automotive systems even in case of failure of the main power source.